You should look in the Demos folder of LD2000. There are a few "Clock and timer examples" that illustrate how to create your own countdown clocks of various forms in Showtime. There is a separate program called "Showclock" that can be used to generate a clock if that's what you want to do, or you can integrate this clock as part of your Showtime show if you wish.

Every year, around December, we remind people about this feature in the LD2000 software. You should take a look at the "What's new at Pangolin" section of our website, toward the end of each year.